CN110283080A - A kind of fluorine-containing benzophenone derivates and its preparation method and application - Google Patents

Abstract

The present invention provides a fluorine-containing benzophenone derivative and a preparation method and application thereof. Preparation method of derivatives: two fluorine-containing benzophenone derivatives 1 and 2 are synthesized by reacting 2,4-dihydroxybenzophenone with 3,4,5-trifluorobenzoyl chloride as raw material. It has the advantages of simple preparation, mild reaction and high yield. Derivative 1 can effectively absorb ultraviolet light of 250-360 nm, which can not only enhance the photostability of UV-curable coatings and coatings, but also has the characteristics of good compatibility with resins or monomers, no odor, etc.; it is also beneficial to ultraviolet light. Storage of cured coatings. Derivative 2 introduces a fluorine atom on the basis of the benzophenone structural skeleton, which can utilize the low surface chemical energy of the fluorine atom to enrich the compound to the surface and accelerate the surface polymerization, thereby inhibiting the phenomenon of oxygen inhibition. The two derivatives synthesized in the present invention can be respectively used as ultraviolet light absorbers and ultraviolet light initiators in the fields of photocurable compositions such as coatings, inks, adhesives and the like.

Description

A kind of fluorine-containing benzophenone derivative and its preparation method and application

technical field

The invention relates to benzophenone derivatives, in particular to a fluorine-containing benzophenone derivative and a preparation method and application thereof.

Background technique

When daily decorative materials such as organic films, coatings and plastic products are used outdoors, these polymer materials are easily degraded by sunlight, resulting in reduced gloss, brittleness, and cracks. Therefore, it is necessary to add UV absorbers to reduce UV light. Deterioration reaction, enhanced weather resistance, provide more complete protection performance. Ultraviolet absorbers are mainly composed of structures containing π-conjugated systems in the molecules, and use their specific structures to absorb ultraviolet rays and release or consume energy in the form of heat energy or harmless low-energy radiation. Commonly used ultraviolet absorbers are benzophenone, There are three types of benzotriazoles and triazines. Benzophenones are the most widely used category, and are widely used in plastics, inks, paints, coatings and other industries because of their good compatibility with other materials. However, benzophenone UV absorbers have small relative molecular weight, poor compatibility with polymer materials, or are volatile during the processing of polymer materials, and have disadvantages such as migration, blooming, and crystallization in products, which makes the material Performance is not as expected. Therefore, people put forward higher requirements for UV absorbers in practical applications, and expect stable and efficient products to appear.

On the other hand, benzophenone is also a common type of hydrogen abstraction photoinitiator, which is cheap, simple to synthesize and easy to store, and is widely used in UV-curable coatings. However, in the curing process, the phenomenon of oxygen inhibition is obvious, and there are easily migrated curing by-derivatives, and the cured film is prone to yellowing. Therefore, with the rapid development of the industry, on the basis of the benzophenone molecular skeleton, through reasonable molecular design and research on the relationship between molecular structure and its properties, we have developed high-efficiency, low-toxicity, low mobility and can inhibit oxygen inhibition. Phenomenal photoinitiators have broad application prospects.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a fluorine-containing benzophenone derivative and a preparation method thereof in view of the problems existing in the prior art. The invention has the advantages of simple preparation operation, mild reaction conditions and high total yield, and the synthesized fluorine-containing benzophenone derivatives can be used as ultraviolet light absorbers or as ultraviolet light initiators.

The fluorine-containing benzophenone derivatives provided by the present invention have structural formula 1 or 2:

The reaction formula is as follows:

Its preparation method comprises the following steps:

1) Add 2,4-dihydroxybenzophenone to the container, dissolve it with an organic solvent, slowly add triethylamine, stir evenly under ice-water bath conditions, and then dropwise add 3,4,5-trifluorobenzene Formyl chloride, stirring and reacting for 6 to 24 hours;

2) After the reaction is completed, add water to the reaction solution and extract with ethyl acetate, collect the organic phase, wash with water, dry, and remove the organic solvent by rotary evaporation; then use a chromatographic silica gel column to separate and purify to obtain fluorine-containing diphenylmethane respectively. Ketone Derivative 1 and Fluorine-Containing Benzophenone Derivative 2.

The molar ratio of 2,4-dihydroxybenzophenone, triethylamine and 3,4,5-trifluorobenzoyl chloride in step 1) is 1:1.4～2:1.2～2.5, preferably 1:1.5 :2;

The organic solvent described in step 1) is tetrahydrofuran or dichloromethane, preferably dichloromethane;

The reaction time described in step 1) is preferably 12 hours.

Step 2) The eluent of the chromatography silica gel column is petroleum ether and ethyl acetate in a volume ratio of 1-10:1, preferably a volume ratio of 3-7:1.

The invention uses 2,4-dihydroxybenzophenone as a raw material, reacts with 3,4,5-trifluorobenzoyl chloride to rapidly synthesize two fluorine-containing benzophenone derivatives. The synthesis method has the advantages of simple operation, mild reaction conditions and high overall yield. Derivative 1 can effectively absorb ultraviolet light of 250-360 nm, enhance the light stability of UV-curable coatings and coatings, and has the characteristics of good compatibility with resins or monomers, no odor, etc. It is also beneficial to UV-curable coatings of storage. At the same time, fluorine atoms with low surface chemical energy are introduced into the derivative 2 on the basis of the benzophenone structure skeleton, so that the compound can be enriched to the surface, which can accelerate the surface polymerization, thereby inhibiting the phenomenon of oxygen inhibition. The fluorine-containing benzophenone derivatives synthesized by the invention can be respectively used as ultraviolet light absorbers and ultraviolet light initiators in the fields of photocurable compositions such as coatings, inks, adhesives and the like.

Description of drawings

Fig.1 UV absorption spectrum of 2-hydroxy-4-(3,4,5-trifluorobenzoyloxy)benzophenone

Fig.2 UV absorption spectrum of 2,4-bis(3,4,5-trifluorobenzoyloxy)benzophenone

Detailed ways

Example 1

Add 0.214g (1mmol) of 2,4-dihydroxybenzophenone and 0.150g (1.5mmol) of triethylamine to the container, dissolve them with 3ml of dichloromethane, and slowly add 0.388g (2mmol) under ice-water bath conditions ) of 3,4,5-trifluorobenzoyl chloride, and the reaction was stirred for 12 hours. After the reaction, add water to the reaction solution and extract with ethyl acetate, collect the organic phase, wash with water, dry with anhydrous sodium sulfate, and remove the organic solvent by rotary evaporation; and take petroleum ether and ethyl acetate (volume ratio 5:1) as The eluent was separated by silica gel column chromatography to obtain derivative 1 and derivative 2.

2-Hydroxy-4-(3,4,5-trifluorobenzoyloxy)benzophenone (derivative 1): white solid, yield: 45%, mp 25-27°C. ¹ H NMR (600 MHz, CDCl ₃ ) δ 12.33 (s, 1H), 7.88 (t, J=7.0 Hz, 2H), 7.75-7.69 (m, 3H), 7.64 (t, J=7.5 Hz, 1H) , 7.55 (t, J=7.7Hz, 2H), 6.97 (d, J=2.3Hz, 1H), 6.78 (dd, J=8.8, 2.3Hz, 1H). ¹³ C NMR (151MHz, CDCl ₃ )δ200. _{78,164.86,161.58,156.02,152.08,150.40,137.65,135.09,132.21,129.10,128.64,117.58,115.08,114.96,112.43,111.22.HRMS} (ESI) _{[ M} ⁺ _H ] :373.0609,found 373.0682.

2,4-bis(3,4,5-trifluorobenzoyloxy)benzophenone (derivative 2): white solid, yield: 30%, mp 105-108°C. ¹ H NMR (600MHz, CDCl ₃ )δ7.93-7.86(m,2H),7.81(d,J=7.2Hz,2H),7.74(t,J=8.6Hz,1H),7.61-7.54(m,1H),7.50-7.43 (m,4H),7.38–7.32(m,2H). ¹³ C NMR (151MHz, CDCl ₃ )δ193.52,164.86,161.77,152.88,149.26,137.39,135.05,133.40,132.00,129.73,129.42,129.13,128. 128.52, 119.40, 116.80, 112.35, 111.22.

The UV absorption of Derivative 1 and Derivative 2 were measured and analyzed at the same time. The results showed that compared with benzophenone, these compounds have better UV absorption properties and can effectively absorb UV light at 250-360 nm and 250-300 nm. , the UV spectrum is shown in Figure 1 and Figure 2.

The following examples are used to specifically illustrate the application of derivative 1, namely 2-hydroxy-4-(3,4,5-trifluorobenzoyloxy) benzophenone as a UV absorber in UV-curable coatings, but Not limited to the use of the following examples.

Example 2: Performance Evaluation of Derivative 1 for Ultraviolet Light Absorbers

Experimental recipe:

Working conditions:

In a glass container equipped with a stirrer, add 50 g of epoxy propylene carboxylic acid resin, 44 g of 1,6-hexanediol diacrylate, 3 g of photoinitiator (1173), 2 g of triethanolamine, 2-hydroxy-4-(3 , 1 g of 4,5-trifluorobenzoyloxy) benzophenone, stir to make it disperse uniformly and transparently, and stand for 5-10 minutes to obtain a transparent free radical photocurable coating. The paint is divided into three parts, one part is put into a transparent glass bottle with a cover for daily indoor storage; one part is put into a transparent glass bottle with a cover for indoor light-proof storage; the other part is coated on a glass plate with an applicator, and the film is The thickness was 75 μm and then cured by a UV curing machine at a speed of 5 meters per minute (approximately 5 seconds of exposure time).

Comparative Example 1 (without adding UV absorber)

Experimental recipe:

Working conditions are the same as in Example 2

Comparative example 2 (without adding photoinitiator)

Experimental recipe:

Working conditions are the same as in Example 2

Comparative example 3 (adding commercially available ultraviolet absorber UV-0)

Experimental recipe:

Working conditions are the same as in Example 2

Table 1 Evaluation of storage results after preparation of UV-curable coatings

experiment 30min 2h 6h (protect from light) 30h 72h Example 2 uniform and transparent uniform and transparent uniform and transparent uniform and transparent slightly cured layer Comparative Example 1 with solidified layer fully cured fully cured fully cured fully cured Comparative Example 2 uniform and transparent uniform and transparent uniform and transparent uniform and transparent uniform and transparent Comparative Example 3 uniform and transparent uniform and transparent uniform and transparent uniform and transparent with solidified layer

It can be seen from Table 1 that the preparation of UV-curable coatings usually needs to be carried out in a dark environment, and the UV-curable coatings will be affected by ultraviolet rays in sunlight, and the storage time cannot be long. Compared with Comparative Example 1, when the paint is prepared, after the derivative 1 of the present invention is added as an ultraviolet absorber, no stricter light-shielding conditions are required. When only the ultraviolet absorber UV-0 was added to the formula of Comparative Example 3, there were many cured layers after storage for 72 hours, while Example 2 had slightly cured layers. The results showed that the ultraviolet absorption effect of Derivative 1 was better than that of commercially available ultraviolet absorption. agent UV-0.

The cured coating of above-mentioned embodiment 2, comparative example 1-3 composition is carried out performance test:

a: Surface dry time test: refers to dry method or cotton ball method.

b: Hardness test: The pencil hardness method is tested according to GB/T6739-1996. Use the coating film pencil scratch hardness tester to observe the scratch marks of the paint film, and take the pencil without scratches as the pencil hardness of the coating film.

c: Adhesion test: cross-cut method (refer to GB 9286-88). The adhesion of the coating film was judged by the cross-cut test method. According to the degree of damage, it can be divided into 6 grades from 0 to 5. The best grade is 0, no small cell on the film surface has fallen off, and grade 5 is extremely poor, and the film surface has severe peeling.

Table 2 Evaluation results of cured coating properties

experiment Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Exterior smooth and transparent smooth and transparent Uncured with pinholes hardness 5H 3H - 4H adhesion 1 2 - 2

It can be seen from Table 2 that when only Derivative 1 is added to the coating and no photoinitiator is added, the curing does not form a film (Comparative Example 2), indicating that Derivative 1 does not participate in the curing film-forming reaction and exists stably in the system; on the other hand , On the basis of common UV-curable coating formulations, when Derivative 1 is added, the hardness and adhesion of the cured film are improved. The cured film obtained in Example 2 has a firm film layer, smooth and uniform surface, and no irritating odor. Features.

Derivative 1 in the present invention is easy to prepare and easy to obtain raw materials; it can effectively absorb ultraviolet light of 250-360 nm with strong absorption intensity, and has the characteristics of good compatibility with resins and monomers, and no odor. It hardly participates in the curing of free radical systems during the curing process, which enhances the light stability of coatings and cured coatings. It is suitable for application in curing compositions such as coatings, inks and adhesives. It is a kind of UV absorber with development prospect.

The following examples are the curing performance of the derivative 2 of the present invention, namely 2,4-bis(3,4,5-trifluorobenzoyloxy)benzophenone as a free-radical photoinitiator and the commercially available free-radical type Comparison of the curing performance of photoinitiator 1173: the oligomer used is modified epoxy acrylate (UV1005-65, produced by Zhongshan Qianqi Chemical Factory), and the monomer is 1,6-hexanediol diacrylate ( HDDA Zhongshan Qiancong Chemical Plant).

Example 3: Application performance evaluation of derivative 2

Experimental recipe:

working conditions

Under light-proof conditions, add 20.03 g of 2,4-bis(3,4,5-trifluorobenzoyloxy) benzophenone and 0.5 g of modified epoxy acrylate (UV1005-65) to a glass container , 0.45 g of 1,6-hexanediol diacrylate (HDDA), 0.02 g of triethanolamine, and stir to a transparent coating liquid. The mixture was coated on a glass plate with an applicator, and the film thickness was 75um, and the mixture was irradiated and cured in a medium pressure mercury lamp, and the power of the mercury lamp was 400W.

Comparative Example 4: Application Performance Evaluation of Photoinitiator 1173

Experimental recipe:

Working conditions are the same as in Example 3

The coating films of above-mentioned embodiment 3 and comparative example 4 compositions are tested for performance:

a Surface dry time test: refers to dry method or cotton ball method.

b hardness test: pencil hardness test according to GB/T6739-1996. Use the coating film pencil scratch hardness tester to observe the scratch marks of the paint film, and take the pencil without scratches as the pencil hardness of the coating film.

c Adhesion test: cross-cut method (refer to GB 9286-88). The adhesion of the coating film was judged by the cross-cut test method. According to the degree of damage, it can be divided into 6 grades from 0 to 5. The best grade is 0, no small cell on the film surface has fallen off, and grade 5 is extremely poor, and the film surface has severe peeling.

The evaluation results are shown in Table 1.

Table 3 Comparison of application performance between derivative 2 and 1173

It can be seen from the test results in the above table that the curing speed of the derivative 2 of the present invention is relatively slow, but the film-forming hardness and adhesion are better than those of the commercially available free radical type photoinitiator 1173. The possible reason is that the initiator has a high concentration on the surface during the polymerization process, and reacts with oxygen to form a protective film, which can effectively overcome the oxygen inhibition. While the concentration at the bottom is relatively low, the polymerization time of the initiating system is longer, but a cured film with strong adhesion can be formed.

Claims (9)

1. a kind of fluorine-containing benzophenone derivates, which is characterized in that structural formula is 1 or 2:

2. a kind of preparation method of fluorine-containing benzophenone derivates, which is characterized in that reaction equation is as follows:

3. a kind of preparation method of fluorine-containing benzophenone derivates, which comprises the steps of:

1) 2,4-DihydroxyBenzophenone is added in a reservoir, after being dissolved with organic solvent, triethylamine is slowly added to, in ice 3,4,5- trifluorobenzoyl chlorides are added dropwise under water bath condition after mixing evenly, are stirred to react 6~24 hours；

2) after reaction, add water into reaction solution and be extracted with ethyl acetate, collect washing, drying after organic phase, and rotate Remove organic solvent；It recycles chromatography silica gel column to carry out separating-purifying, that is, respectively obtains fluorine-containing benzophenone derivates 1 and contain The benzophenone derivates 2 of fluorine.

4. a kind of preparation method of fluorine-containing benzophenone derivates as claimed in claim 3, which is characterized in that described 2, The molar ratio of 4- dihydroxy benaophenonel, triethylamine and 3,4,5- trifluorobenzoyl chloride is 1:1.4~2:1.2~2.5.

5. a kind of preparation method of fluorine-containing benzophenone derivates as claimed in claim 3, which is characterized in that in step 1) The organic solvent is tetrahydrofuran or methylene chloride.

6. a kind of preparation method of fluorine-containing benzophenone derivates as claimed in claim 3, which is characterized in that step 1) institute The reaction time stated preferably 12 hours.

7. a kind of preparation method of fluorine-containing benzophenone derivates as claimed in claim 3, which is characterized in that in step 2) The eluant, eluent of the chromatography silica gel column is the petroleum ether and ethyl acetate of 1~10:1 of volume ratio.

8. a kind of application of the fluorine-containing benzophenone derivates as described in claim 1 as UV absorbers, described to spread out Biology is the derivative of structural formula 1.

9. a kind of application of the fluorine-containing benzophenone derivates as described in claim 1 as ultraviolet initiator, described to spread out Biology is the derivative of structural formula 2.